Stock photos...?

Seriously I would not waste my time. The chances of you making enough to cover the effort that's needed to keep feeding the agencies with stock they will take and can sell is very small.

I've pulled out of them all, there are those that keep feeding the monster and get a return, the vast majority get next to nothing back.

I bet the libraries make a fortune out of not paying anyone a penny for a lot of images. They have a minimum earn before they let you take your money. I would guess a large percentage never get that minimum or get fed up looking for it that they give up checking to see if it's there.

They are statistics they never publish.

I used to do well with libraries before they decided you can never sell to cheaply. Now I just sell direct, but that's a full time job targeting and marketing.

Give it a try for fun if you have a few spare hours and expect nothing much in financial reward back.

You most likely would do better selling images of the bands to the fans, either via ebay or your own site. You could link in with a lab to do the printing, handout the web address at gigs. That way you stand a chance of a worthwhile return if priced correctly.